1. Field of the Invention
The present invention relates to door locks. More particularly, this invention relates to the locking mechanism in door locks in which the handle is allowed to "free-wheel", i.e., rotate without retracting the latchbolt, when the mechanism is locked.
2. Description of Related Art
Doors are much easier to open when the door handle is shaped as a lever handle rather than a conventional door knob. For this reason, lever handles are preferred in some applications, and they may be required under applicable regulations for certain doors in public buildings to facilitate access by the disabled and the elderly.
However, the lever shape of the door handle allows much greater force to be applied to the internal locking mechanism of the door than can be applied with a round door knob. In most door locks, the locking mechanism prevents the door knob from turning when the door is locked. When a round door knob is replaced by a lever handle, the greater leverage available from such a handle may allow a vandal or thief to break the internal components of the door lock by standing or jumping on the lever end of the handle. This problem is particularly acute for cylindrical locks which have less internal room than mortise type locks to accommodate heavy duty locking components.
To address this problem, the present invention has been designed such that the outer lever handle is disengaged from the locking mechanism and allowed to free-wheel when the door lock mechanism is locked. This allows the lever handle to rotate freely without operating the locking mechanism and prevents the lever handle from being used to overstress the internal components of the lock.
Free-wheeling door locks which have previously been developed have been expensive due to the large number of parts, the multiple manufacturing steps needed to make the parts and the difficulty of assembly of the lock at the factory. The present invention addresses these problems through a design which includes relatively fewer parts and simpler parts that can be manufactured with fewer steps and which are quickly and easily assembled in the factory and in the field.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a free-wheeling lever handle lock mechanism that is relatively less expensive to construct and assemble than prior art free-wheeling lock mechanisms.
It is another object of the present invention to provide a free-wheeling lever handle lock mechanism that has fewer components than prior art free-wheeling lock mechanisms, and where the components are easy to manufacture and assemble.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.